U.S. patent application number 13/814480 was filed with the patent office on 2013-05-30 for heating system.
The applicant listed for this patent is Hiroshi Aoki. Invention is credited to Hiroshi Aoki.
Application Number | 20130134745 13/814480 |
Document ID | / |
Family ID | 45559403 |
Filed Date | 2013-05-30 |
United States Patent
Application |
20130134745 |
Kind Code |
A1 |
Aoki; Hiroshi |
May 30, 2013 |
HEATING SYSTEM
Abstract
A seat heater has heater electrodes in a film shape and a sensor
electrode in a film shape. When detecting an occupant through the
sensor electrode, the heater electrodes are disconnected from a
heater unit to cause those electrodes to be substantially insulated
from a vehicle. This makes it possible to detect the occupant
seated on a seat without being affected by the heater electrodes.
According to such a structure, it becomes possible to warm the
occupant and to precisely detect the occupant.
Inventors: |
Aoki; Hiroshi; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Aoki; Hiroshi |
Tokyo |
|
JP |
|
|
Family ID: |
45559403 |
Appl. No.: |
13/814480 |
Filed: |
July 27, 2011 |
PCT Filed: |
July 27, 2011 |
PCT NO: |
PCT/JP2011/067169 |
371 Date: |
February 5, 2013 |
Current U.S.
Class: |
297/180.12 |
Current CPC
Class: |
B60N 2/002 20130101;
B60N 2/5685 20130101 |
Class at
Publication: |
297/180.12 |
International
Class: |
B60N 2/56 20060101
B60N002/56 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 5, 2010 |
JP |
2010-176823 |
Claims
1. A heating system for warming an occupant seated on a seat of a
vehicle, the heating system comprising: a heating element disposed
in the seat; heater electrodes connected to the heating element; a
sensor electrode disposed in the seat; a supply unit that supplies
power to the heating element; a connection unit that intermittently
connects the supply unit with the heater electrodes; a measurement
unit that measures an impedance between the sensor electrode and
the vehicle when the supply unit is not connected to the heater
electrodes; and a detection unit that detects the occupant seated
on the seat based on the impedance measured by the measurement
unit.
2. The heating system according to claim 1, wherein the heater
electrodes overlap the heating element or the heater
electrodes.
3. The heating system according to claim 1, wherein the measurement
unit measures, as an impedance correlation value, capacitance
between the sensor electrode and the vehicle from an AC voltage
applied between the sensor electrode and the vehicle and a current
or a voltage input into the sensor electrode in accordance with a
change in the impedance.
4. The heating system according to claim 3, wherein the measurement
unit measures, as the capacitance that is the impedance correlation
value, a quadrarure component of the current to the AC voltage.
5. The heating system according to claim 4, wherein the measurement
unit measures an in-phase component of the current to the AC
voltage, and the detection unit detects the occupant seated on the
seat based on a comparison result between a threshold defined based
on a relationship between the in-phase component and the quadrarure
component and the capacitance.
6. The heating system according to claim 1, further comprising a
temperature detecting sensor that detects a temperature of the seat
near the heating element, wherein the detection unit detects the
occupant based on a temperature of the seat detected by the
temperature detecting sensor and a comparison result between the
threshold and the capacitance.
7. The heating system according to claim 1, wherein the connection
unit alternately connects the heater electrodes with the supply
unit and a power source that applies a voltage to the heater
electrodes.
8. The heating system according to claim 7, wherein the power
source applies a voltage with a same phase as a phase of a voltage
applied to the sensor electrode.
9. The heating system according to claim 7, wherein the power
source applies a voltage with a different phase from a phase of a
voltage applied to the sensor electrode.
10. The heating system according to claim 2, wherein the
measurement means unit measures, as an impedance correlation value,
capacitance between the sensor electrode and the vehicle from an AC
voltage applied between the sensor electrode and the vehicle and a
current or a voltage input into the sensor electrode in accordance
with a change in the impedance.
11. The heating system according to claim 10, wherein the
measurement unit measures, as the capacitance that is the impedance
correlation value, a quadrarure component of the current to the AC
voltage.
12. The heating system according to claim 11, wherein the
measurement unit measures an in-phase component of the current to
the AC voltage, and the detection unit detects the occupant seated
on the seat based on a comparison result between a threshold
defined based on a relationship between the in-phase component and
the quadrarure component and the capacitance.
Description
TECHNICAL FIELD
[0001] The present invention relates to a heating system, and more
particularly, to a heating system for warming an occupant.
BACKGROUND ART
[0002] Occupant restraining systems represented by seat belts and
air-bag systems have become smaller and of lower cost, and are
nowadays installed in almost all kinds of vehicles as standard
equipment. This kind of occupant restraining system should be able
to detect the occupant of a seat with accuracy for urging him/her
to wear the seat belt or for controlling the air-bag according to
the presence/absence of the occupant.
[0003] On the other hand, vehicles used in cold climates sometimes
have a heating element installed in the seats for warming the
occupants. The seats of vehicles generally have a seat surface made
of a low heat conductive material such as urethane foam. Therefore,
for warming the occupant efficiently, the heating element should be
placed near the seat surface.
[0004] Then, a two-tier structure unit formed by laminating a
heating element film and a sensor film has been proposed (for
example, see Patent Literature 1).
PRIOR ART LITERATURE
Patent Literature
[0005] Patent Literature 1: Japanese National Publication No.
2004-504082
DISCLOSURE OF THE INVENTION
Problem to be Solved by the Invention
[0006] When, however, a heater for warming an occupant is disposed
in a seat together with a sensor electrode, the sensor electrode is
electrically connected to the heater, and the capacitance between
the sensor electrode and the heater may become remarkably larger
than the capacitance between an occupant as a detection target and
the sensor electrode. In this case, the change in the capacitance
changing depending on the presence/absence of the sitting occupant
becomes remarkably smaller than the capacitance between the sensor
electrode and the ground, and thus the detection precision of an
occupant seated on the seat may decrease.
[0007] In consideration of the foregoing, it is an objective of the
present invention to improve the detection precision of an
occupant.
Means for Solving the Problem
[0008] In order to achieve the above objective, a heating system of
the present invention is:
[0009] a heating system for warming an occupant seated on a seat of
a vehicle, the heating system comprising:
[0010] a heating element disposed in the seat;
[0011] heater electrodes connected to the heating element;
[0012] a sensor electrode disposed in the seat;
[0013] supply means for supplying power to the heating element;
[0014] connection means for intermittently connecting the supply
means with the heater electrodes;
[0015] measurement means for measuring an impedance between the
sensor electrode and the vehicle when the supply means is not
connected to the heater electrode; and
[0016] detection means for detecting the occupant seated on the
seat based on the impedance measured by the measurement means.
[0017] The heater electrodes may overlap the heating element or the
heater electrodes.
[0018] The measurement means may measure, as an impedance
correlation value, capacitance between the sensor electrode and the
vehicle from an AC voltage applied between the sensor electrode and
the vehicle and a current or a voltage input into the sensor
electrode in accordance with a change in the impedance.
[0019] The measurement means may measure, as the capacitance that
is the impedance correlation value, a quadrarure component of the
current to the AC voltage.
[0020] The measurement means may measure an in-phase component of
the current to the AC voltage, and the detection means may detect
the occupant seated on the seat based on a comparison result
between a threshold defined based on a relationship between the
in-phase component and the quadrarure component and the
capacitance.
[0021] The heating system may further have a temperature detecting
sensor that detects a temperature of the seat near the heating
element, in which the detection means may detect the occupant based
on a temperature of the seat detected by the temperature detecting
sensor and a comparison result between the threshold and the
capacitance.
[0022] The connection means may alternately connect the heater
electrodes with the supply means and a power source that applies a
voltage to the heater electrodes.
[0023] The power source may apply a voltage with a same phase as a
phase of a voltage applied to the sensor electrode.
[0024] The power source may apply a voltage with a different phase
from a phase of a voltage applied to the sensor electrode.
Effects of the Invention
[0025] According to the present invention, the electrode of the
heater for warming an occupant can be disconnected from the power
source when an occupant is detected. Accordingly, the heater
electrode and the heating element are insulated from the ground,
and thus the occupant can be detected precisely without being
affected by the heater electrode or the like.
BRIEF DESCRIPTION OF DRAWINGS
[0026] FIG. 1 is a block diagram of the heating system according to
Embodiment 1;
[0027] FIG. 2 is an exploded perspective view of a seat heater;
[0028] FIG. 3 is a cross-sectional view of the seat heater;
[0029] FIG. 4 is an illustration showing a vehicle seat and the
occupant seated on the seat;
[0030] FIG. 5 is a diagram schematically showing the electric
circuit formed when there is no occupant seated on the seat;
[0031] FIG. 6 is a diagram showing an equivalent circuit to the
electric circuit in FIG. 5;
[0032] FIG. 7 is a diagram schematically showing the electric
circuit formed when there is an occupant seated on the seat;
[0033] FIG. 8 is a diagram showing an equivalent circuit to the
electric circuit in FIG. 7;
[0034] FIG. 9 is a diagram showing an equivalent circuit to the
electric circuit in FIG. 8;
[0035] FIG. 10 is a graphical representation showing a relationship
between the quadrature component and the in-phase component;
[0036] FIG. 11 is a block diagram of the heating system according
to Embodiment 2;
[0037] FIG. 12 is a diagram showing an equivalent circuit to the
electric circuit in FIG. 11;
[0038] FIG. 13 is a plan view of a seat heater according to a
modified embodiment; and
[0039] FIG. 14 is a cross-sectional view at a line A-A of the seat
heater in FIG. 13.
MODE FOR CARRYING OUT THE INVENTION
Embodiment 1
[0040] Embodiment 1 of the present invention will be described
hereafter with reference to the drawings. FIG. 1 is a diagram
illustrating a general structure of a heating system 10 according
to the present embodiment. The heating system 10 is a system for
warming an occupant seated on, for example, a seat of a vehicle. As
shown in FIG. 1, this heating system 10 has a seat heater 20, a
heater unit 32, a detection unit 33, and a switch SW1.
[0041] FIG. 2 is an exploded perspective view of the seat heater
20. As shown in FIG. 2, the seat heater 20 has a sensor electrode
25, two heater electrodes 21 and 22, heating elements 23 and 24
formed between the heater electrode 21 and the heater electrode 22,
and insulation sheets 26, 27, and 28 covering the respective
members.
[0042] The insulation sheets 26, 27, and 28 are each, for example,
a sheet formed of a PET (polyethylene tephthalate), or a Mylar
film. Moreover, the insulation sheets 26, 27, and 28 which are a
sheet formed of a material with flexibility like polyimide,
polyvinyl chloride, or a silicon rubber can be applied. Those
insulation sheets 26, 27, and 28 are shaped into a rectangle having
a lengthwise direction in a Y-axis direction.
[0043] The heater electrode 21 is formed on a top face of the
insulation sheet 26. As shown in FIG. 2, the heater electrode 21 is
formed of a silver paste or copper and is patterned into a U shape.
The heater electrode 21 has a connection part 21a formed at a -X
side thereof and connected to the switch SW1.
[0044] The heater electrode 22 is shaped into a U shape like the
heater electrode 21, and has a connection part 22a formed at a -X
side thereof and connected to the switch SW1. The pattern of this
heater electrode 22 at a +Y side is surrounded by the heater
electrode 21.
[0045] Those heater electrodes 21 and 22 can be formed on the top
face of the insulation seat 26 by bonding a copper foil on the top
face of the insulation sheet 26, and by etching and patterning such
a copper foil.
[0046] The heating elements 23 and 24 are each shaped into a
rectangle having the lengthwise direction in an X-axis direction,
and are formed in such a manner as to adjoin with each other in the
Y-axis direction. As shown in FIG. 3, the heating elements 23 and
24 are each formed between the top face of the heater electrode 21
and the top face of the heater electrode 22.
[0047] Those heating elements 23 and 24 can be formed on the top
face of the insulation sheet 26 by applying a
temperature-resistance paste or a carbon paste from the heater
electrode 21 to the heater electrode 22 on the top face of the
insulation sheet 26 where the heater electrodes 21 and 22 are
formed and by letting such a paste to be cured.
[0048] The sensor electrode 25 is formed in such a manner as to run
on the top face of the insulation sheet 27 in a zig-zag manner. The
sensor electrode 25 is also formed of copper like the heater
electrodes 21 and 22. This sensor electrode 25 can be formed by,
for example, bonding a copper foil on the top face of the
insulation sheet 27, and by etching and patterning this copper
foil.
[0049] As is clear from FIG. 2, the insulation sheets 26 to 28
constructing the seat heater 20 are integrated with each other by
bonding the insulation sheet 27 formed with the sensor electrode 25
on the top face of the insulation sheet 26 formed with the heater
electrodes 21 and 22, and by bonding the insulation sheet 28 on the
top face of the insulation sheet 27.
[0050] FIG. 3 is a diagram illustrating a ZY cross-section of the
seat heater 20. As shown in FIG. 3, the heater electrodes 21 and
22, the heating elements 23 and 24, and the sensor electrode 25 are
insulated by the insulation sheet 27. Moreover, the heater
electrodes 21 and 22 and the heating elements 23 and 24 are covered
by the insulation sheet 26, and the sensor electrode 25 is covered
by the insulation sheet 28.
[0051] FIG. 4 is a diagram illustrating a seat 101 of a vehicle 100
together with an occupant 120 seated on the seat 101. As shown in
FIG. 4, the seat heater 20 employing the above-explained structure
is disposed right below the seat cover forming a seating surface
101a of the seat 101.
[0052] Returning to FIG. 1, the heater unit 32 is connected to the
heater electrodes 21 and 22 through the switch SW1. This heater
unit 32 supplies electrical energy from an unillustrated battery
loaded on the vehicle 100 to the heating elements 23 and 24 through
the heater electrodes 21 and 22. Accordingly, current flows through
the heating elements 23 and 24, and thus the heating elements 23
and 24 generate heat.
[0053] The switch SW1 intermittently disconnects the heater unit 32
with the heater electrodes 21 and 22. When the heater unit 32 is
disconnected from the heater electrodes 21 and 22, the heater
electrodes 21 and 22 and the heating elements 23 and 24 are
electrically insulated from the vehicle 100.
[0054] The detection unit 33 monitors the potential of the heater
electrode 21, and obtains the capacitance between the sensor
electrode 25 and the vehicle 100 when the heater unit 32 is
disconnected from the heater electrodes 21 and 22 by the switch
SW1, and determines whether or not the occupant 120 is seated on
the seat 101 based on the obtained capacitance. Next, the detection
unit 33 outputs the determination result to, for example, an
external device.
[0055] FIG. 5 is a diagram schematically showing an electric
circuit formed when no occupant 120 is seated on the seat 101. In
the electric circuit formed when no occupant is seated on the seat
101, as shown in FIG. 5, the sensor electrode 25 is connected to
the heater electrodes 21 and 22 through capacitors C4 and C6, and
is connected to the heating elements 23 and 24 through a capacitor
C5. The heater electrodes 21 and 22 are connected to the vehicle
100 through capacitors C1 and C3. Moreover, the heating elements 23
and 24 are connected to the vehicle 100 through a capacitor C2.
[0056] FIG. 6 is an equivalent circuit of the circuit shown in FIG.
5. The circuit shown in FIG. 5 can be substituted by the equivalent
circuit shown in FIG. 6. A resistor Ra configuring the equivalent
circuit of FIG. 6 indicates resistance or the like between the
heater electrode 21 and the heater electrode 22. A resistor Rb
indicates resistance of the sensor electrode 25. Furthermore,
capacitors Ca and Cb are composite of capacitors C1, C2 and C3.
Capacitors Cc and Cd are composite of capacitors C4, C5, and
C6.
[0057] As is clear from the equivalent circuit shown in FIG. 6,
composite capacitance C.sub.T1 between the sensor electrode 25 and
the vehicle 100 are defined by capacitors Ca, Cb, Cc, and Cd.
[0058] FIG. 7 is a diagram schematically showing an electric
circuit formed when the occupant 120 is seated on the seat 101. As
is clear when FIG. 7 is compared with FIG. 5, when the occupant 120
sits down the seat 101, a new circuit having the occupant 120
present therein is formed. The newly formed circuit has a capacitor
C7 indicating capacitance between the sensor electrode 25 and the
occupant 120, and a capacitor C8 indicating capacitance between the
occupant 120 and the vehicle 100.
[0059] The circuit shown in FIG. 7 can be substituted by an
equivalent circuit shown in FIG. 8. The equivalent circuit shown in
FIG. 8 is the equivalent circuit of FIG. 6 which is further added
with capacitors Ce, Cf, and C8 and a resistor Rc. The capacitors Ce
and Cf are capacitors having capacitance that is a half of the
capacitance of the capacitor C7. Moreover, the capacitor C8 is, as
explained above, a capacitor indicating capacitance between the
occupant 120 and the vehicle 100. Furthermore, the resistor Rc
indicates resistance between the occupant 120 and the vehicle
100.
[0060] As is clear from the equivalent circuit of FIG. 8, composite
capacitance C.sub.T2 between the sensor electrode 25 and the
vehicle 100 when the occupant 120 is seated on the seat 101 can be
measured through the following formula (1).
C.sub.T2=C.sub.T1+C8(Ce+Cf)/(Ce+Cf+C8) (1)
[0061] As is clear from the above formula (1), when the occupant
120 sits down the seat 101, the value of the composite capacitance
between the sensor electrode 25 and the vehicle 100 increases by
what corresponds to the capacitance inherent to the capacitors Ce,
Cf, and C8. The detection unit 33 detects the composite capacitance
changing as explained above, and determines whether or not the
occupant 120 is seated on the seat 101 based on the detection
result. The specific structure of the detection unit 33 will be
explained below.
[0062] As shown in FIG. 8, the detection unit 33 has an AC power
source 33a, a quadrature demodulator 33b, and a detector 33c.
[0063] The AC power source 33a converts the voltage of an
unillustrated battery installed on the vehicle 100 into an AC
voltage of substantially 100 kHz, and applies such a voltage
between the sensor electrode 25 and the body of the vehicle
100.
[0064] The quadrature demodulator 33b monitors an AC voltage V
applied between the sensor electrode 25 and the vehicle 100 and
current i supplied to the sensor electrode 25. Next, the quadrature
demodulator 33b outputs information on the in-phase component I of
the current i to the AC voltage V and the quadrarure component Q of
the current i to the AC voltage V to the detector 33c.
[0065] The detector 33c determines whether or not the occupant 120
is seated on the seat 101 based on the value of the in-phase
component I and that of the quadrarure component Q. Next, the
detector 33c outputs a determination result to, for example, an
external device.
[0066] Electric circuits shown in FIG. 6 and FIG. 8 can be regarded
as a circuit shown in FIG. 9. In this case, composite resistance
R.sub.T and composite capacitance C.sub.r between the sensor
electrode 25 and the vehicle 100 can be expressed as following
formulae (2) and (3), respectively. According to the following
formula (2), it becomes clear that the composite capacitance
C.sub.T is equivalent to the quadrarure component Q of the current
i.
C.sub.T=Q (2)
R.sub.T=1/I (3)
[0067] Hence, the detector 33c compares, for example, the value of
the quadrarure component Q with a predetermined threshold value.
Next, when the quadrarure component Q is equal to or larger than
the threshold value, the detector 33c determines that the occupant
120 is seated on the seat 101. Conversely, when the quadrarure
component Q is smaller than the predetermined threshold value, the
detector 33c determines that no occupant 120 is seated on the seat
101.
[0068] According to the present embodiment, when the seating
surface 101a of the seat 101 is wet or when the material of the
seat 101 is moist, the above-explained threshold is set in
consideration of the increase of the capacitance between the sensor
electrode 25 and the vehicle 100. To set such a threshold, a
straight line indicating an IQ characteristic shown in FIG. 10 is
utilized.
[0069] An area AR1 in FIG. 10 is an area where the points defined
by the quadrature component Q and in-phase component I are present
when the occupant 120 is seated on the seat 101. On the other hand,
an area AR2 is an area where the points defined by the quadrature
component Q and in-phase component I are present when the occupant
120 is not seated on the seat 101. The detector 33c determines the
threshold based on a curve L separating the areas AR1 and AR2. For
example, the detector 33c determines that the threshold is b when
the in-phase component I has a value a.
[0070] Then, the detector 33c determines that the occupant 120 is
seated on the seat 101 when the quadrature component Q has a value
greater than the threshold b. On the other hand, the detector 33c
determines that the occupant 120 is not seated on the seat 101 when
the quadrature component Q has a value smaller than the threshold
b. Then, the detector 33c outputs information regarding the above
determination result to, for example, an external device.
[0071] The external device can use the determination result, for
example, for giving a warning to wear the seatbelt or for
controlling the expansion of the air-bag.
[0072] As explained above, the seat heater 20 of the present
embodiment has the heater electrodes 21 and 22 in the film shape,
and the sensor electrode 25 in the film shape. When detecting the
occupant 120 through the sensor electrode 25, the heater electrodes
21 and 22 are disconnected from the heater unit 32, and are
substantially insulated from the vehicle 100. Hence, when detecting
the occupant 120, the detection unit 33 can detect the occupant 120
without being affected by the heater electrodes 21 and 22. This
operation will be explained below in more detail.
[0073] As shown in FIG. 3, the sensor electrode 25 and the heater
electrodes 21 and 22 are distant from each other by what
corresponds to the thickness of the insulation sheet 27, the
capacitances of the capacitors Cc and Cd shown in, for example,
FIG. 6 or FIG. 8 become large. According to the present embodiment,
when detecting the occupant 120, the heater electrodes 21 and 22
are disconnected from the heater unit 32. Hence, the capacitances
of the capacitors Ca and Cb shown in, for example, FIG. 8 become
relatively small in comparison with the capacitances of the
capacitors Cc and Cd. Moreover, the capacitance C.sub.T1 between
the sensor electrode 25 and the vehicle 100 when no occupant 120 is
seated on the seat 101 becomes a relatively small value.
Accordingly, as is clear from formula (1), a difference
(=C8(Ce+Cf)/(Ce+Cf+C8)) between the capacitance C.sub.T2 when the
occupant 120 is seated on the seat 101 and the capacitance
C.sub.T1, when no occupant 120 is seated on the seat 101 becomes
large in comparison with the capacitance C.sub.T1. Hence, the
detection unit 33 can detect the occupant 120 which is hardly
affected by the heater electrodes 21 and 22.
[0074] When the heater electrodes 21 and 22 are connected with the
heater unit 32, the heater electrodes 21 and 22 may be grounded to
the vehicle 100 through the heater unit 32. In this case, the
capacitance between the heater electrodes 21, 22 and the vehicle
100 or between the heater electrode 21 and the sensor electrode 25
becomes large. In this case, also, the occupant 120 seated on the
seat 101 can be detected upon consideration of the capacitance
between the heater electrodes 21, 22 and the occupant 120 and the
capacitance between the heater electrodes 21, 22 and the sensor
electrode 25, and the like.
[0075] According to the present embodiment, the detection unit 33
monitors the potential of the heater electrode 22, thereby
determining whether or not the heater unit 32 is disconnected from
the heater electrodes 21 and 22. The present invention is not
limited to such a configuration, and the detection unit 33 may
determine whether or not the heater unit 32 is disconnected from
the heater electrodes 21 and 22 by monitoring the condition of the
switch SW1.
[0076] Moreover, according to the present embodiment, the detection
unit 33 monitors the potential of the heater electrode 21, thereby
determining whether or not the heater unit 32 is disconnected from
the heater electrodes 21, 22. The present invention is not limited
to this configuration, and the switch SW1 may be operated to
disconnect the heater unit 32 from the heater electrodes 21 and 22
when the detection unit 33 attempts to detect the occupant 120.
[0077] Furthermore, according to the present embodiment, the
threshold for a determination on whether or not the occupant 120 is
seated on the seat 101 is set based on the value of the in-phase
component I output by the quadrature demodulator 33b. The
above-explained determination is carried out based on such a
threshold. Hence, the occupant 120 can be precisely detected.
[0078] According to the present embodiment, the explanation was
given of the case in which the seat heater 20 has the heater
electrodes 21 and 22 of the dual system. The present invention is
not limited to this configuration, and the seat heater 20 may have
heater electrodes of equal to or greater than a triple system.
[0079] According to the present embodiment, both heater electrode
21 and heater electrode 22 are disconnected from the heater unit 32
by the switch SW1. The present invention is not limited to this
case, and only either one of the heater electrode 21 and the heater
electrode 22 may be disconnected. When the seat heater 20 has the
heater electrodes of equal to or greater than the triple system,
only some heater electrodes may be disconnected from the heater
unit 32.
[0080] When detecting the occupant 120, it is appropriate if the
heater electrodes 21 and 22 are disconnected from the heater unit
32 for substantially 0.1 second. Hence, the function of warming up
the occupant 120 is not disturbed.
Embodiment 2
[0081] The heating system according to Embodiment 2 of the present
invention will be described hereafter. A heating system 10A of the
present embodiment differs from the first embodiment that such a
heating system applies an AC voltage to both sensor electrode 25
and heater electrodes 21 and 22 when attempting to detect the
occupant 120.
[0082] FIG. 11 is a block diagram of the heating system 10A of the
present embodiment. As shown in FIG. 11, the heating system 10A has
a switch SW2 and a detection unit 33A.
[0083] The switch SW2 alternately connects the heater electrodes 21
and 22 of the seat heater 20 with the heater unit 32 and the
detection unit 33A, respectively.
[0084] The detection unit 33A constructing the heating system 10A
has AC power sources 34A, 34B, the quadrature demodulator 33b, and
the detector 33c.
[0085] The AC power source 34A applies an AC voltage V1 with an
amplitude of v to both terminals of the sensor electrode 25.
Moreover, the AC power source 34B applies an AC voltage V2 with an
amplitude of v having a different cycle 180 degrees from the AC
voltage V1 to the heater electrodes 21 and 22 when the heater
electrodes 21 and 22 are connected to the detection unit 33A by the
switch SW2.
[0086] FIG. 12 is, for example, an equivalent circuit of a circuit
formed when the heater electrodes 21 and 22 are connected to the
detection unit 33A by the switch SW2. According to the present
embodiment, the AC voltages applied by the AC power sources 34A and
34B have different phases 180 degrees from each other. Hence, a
potential difference between a point P1 and a point P2 at both
terminals of the capacitor Cc in FIG. 12 and a potential difference
between a point P3 and a point P4 at both terminals of the
capacitor Cd become 2v at maximum.
[0087] Hence, a value of current i1 supplied from the AC power
source 34A to the sensor electrode 25 becomes large. Accordingly,
the value of the in-phase component I of the current i1 to the AC
voltage V1 output by the quadrature demodulator 33b and that of the
quadrarure component Q become relatively large.
[0088] Moreover, since the potential difference between the
capacitor Cc and the capacitor Cd becomes large, a current
component originating from the capacitors Cc and Cd among in the
current of the capacitance between the sensor electrode 25 and the
vehicle 100 becomes dominant. In this case, a change in the
capacitances of the capacitors Cc and Cd can be detected by
detecting a change in the quadrarure component Q.
[0089] For example, the insulation sheet 27 present between the
above-explained sensor electrode 25 and the above-explained heater
electrodes 21 and 22 is compressed and deformed in accordance with
the weight of the occupant 120 seated on the seat 101. Hence, by
detecting a change in the quadrarure component Q, a mass or the
like of the object placed on the seat 101, such as the weight of
the occupant 120, can be detected. In this case, when the
insulation sheet 27 is formed of a material easily performing
elastic deformation, the detection precision of the weight or the
like of the occupant 120 can be improved.
[0090] Moreover, according to the present embodiment, the AC
voltages V1 and V2 applied by the AC power sources 34A and 34B have
phases shifted by 180 degrees from each other. The present
invention is not limited to this case, and the detection unit 33
can detect the occupant 120 seated on the seat 101 when the AC
voltages V1 and V2 applied by the AC power source 34A and 34B have
the same phase and amplitude.
[0091] In this case, the potential of the sensor electrode 25 and
the potentials of the heater electrodes 21 and 22 become equal to
each other. That is, the potentials at the points P1 to P4 in FIG.
12 become equal. In this case, no potential difference is caused
between respective both terminals of the capacitors Cc and Cd, it
becomes unnecessary to consider the presence of the heater
electrodes 21 and 22 when detecting the occupant 120 through the
sensor electrode 25. That is, the detection unit 33 can detect the
occupant 120 without being affected by the heater electrodes 21 and
22.
[0092] In this case, also, the capacitances between the heater
electrodes 21 and 22 and the vehicle 100 indicated by the
capacitors Ca and Cb are undetected through the sensor electrode
25. That is, the capacitances between the heater electrodes 21 and
22 and the vehicle 100 are shielded by the heater electrodes 21 and
22. Hence, the detection unit 33 detects only the capacitances
between the sensor electrode 25 and the occupant 120 indicated by
the capacitors Ce and Cf and the capacitance between the occupant
120 and the vehicle 100 indicated by the capacitor C8. Accordingly,
the detection unit 33 can precisely detect the occupant 120.
[0093] As explained above, according to the present embodiment, by
changing the phases of the AC voltages V1 and V2 applied by the AC
power sources 34A and 34B, the detection sensitivity of the
occupant 120 by the sensor electrode 25 can be tuned. Moreover, it
becomes possible to detect the occupant 120 precisely without being
affected by the heater electrodes 21 and 22.
[0094] According to the present embodiment, the occupant 120 is
detected based on the current i1 between the AC power source 34A
and the sensor electrode 25. The present invention is not limited
to this configuration, and the capacitances between the heater
electrodes 21 and 22 and the vehicle 100 indicated as the
capacitors Ca, Cb can be likewise detected by detecting, for
example, current i2 between the AC power source 34B and the heater
electrodes 21 and 22.
[0095] This capacitance increases when, for example, the occupant
120 sits down the seat 101, the seat deforms, and the distance
between the heater electrodes 21 and 22 and the vehicle 100 and the
distance between the heater electrodes 21 and 22 and the component
provided in the vehicle 100 or the like is reduced. Hence, by
detecting a change in the capacitance between the heater electrodes
21 and 22 and the vehicle 100, the weight or the like of the
occupant 120 seated on the seat 101 can be detected. In this case,
the sensor electrode 25 serves as a shield against the heater
electrodes 21, 22. Hence, it becomes possible to detect the weight
or the like of the occupant 120 seated on the seat 101 through the
heater electrodes 21 and 22 without being affected by the
capacitance between the occupant 120 and the sensor electrode
25.
[0096] As explained above, by detecting the current i2, the spatial
dimension of the occupant 120 seated on the seat 101 and that of
the object placed on the seat 101 can be detected through the
sensor electrode 25, and the weight of the occupant 120 seated on
the seat 101 and that of the object placed on the seat 101 can be
detected through the heater electrodes 21 and 22.
[0097] When the heater electrodes 21 and 22 are utilized as a
shield, it is desirable that the heater electrodes 21 and 22 should
have an area equal to or larger than that of the sensor electrode
25, and the respective electrodes should overlap with each other.
When the sensor electrode 25 is utilized as a shield, it is
desirable that the sensor electrode 25 should have an area equal to
or larger than the heater electrodes 21 and 22, and the respective
electrodes should overlap with each other. In this case, when the
respective electrodes are in the same shape, the shielding effect
is maximized.
[0098] Moreover, only either one of the heater electrodes 21 and 22
can be utilized as a shield. Furthermore, when the seat heater 20
has heater electrodes of equal to or greater than a triple system,
some heater electrodes may be utilized as a shield.
[0099] According to the present embodiment, the explanation was
given of the case in which the phase of the voltage applied by the
AC power source 34A and the phase of the voltage applied by the AC
power source 34B have a difference (phase difference) that is 180
degrees from each other, but it is unnecessary that the phase
difference between both voltages is always 180 degrees.
[0100] The embodiments of the present invention were explained
above, but the present invention is not limited to the
above-explained embodiments. For example, according to the present
embodiment, as is clear from FIG. 3 and FIG. 4, the sensor
electrode 25 is disposed at a location near the occupant 120, while
the heater electrodes 21 and 22 are disposed at locations distant
from the occupant 120. The present invention is not limited to this
configuration, and the heater electrodes 21 and 22 may be disposed
at locations near the occupant 120, while the sensor electrode 25
may be disposed at a location distant from the occupant 120. In
this case, it becomes possible to warm the occupant 120
efficiently.
[0101] The quadrature demodulator 33b and the detector 33c may be
connected to either one of the AC power sources 34A and 34B.
Moreover, the quadrature demodulator 33b and the detector 33c may
be connected to both of the AC power sources 34A and 34B, and the
values of respective output voltages of the AC power sources 34A
and 34B and the phases thereof may be changed to obtain the values
of the in-phase component I and the quadrarure component Q.
[0102] According to the above-explained embodiments, the
explanation was given of the case in which the heater electrodes
21, 22 of the seat heater 20 and the sensor electrode 25 are formed
on respective separate insulation sheets. The present invention is
not limited to this case, and the heater electrodes 21, 22 and the
sensor electrode 25 may be formed on the same insulation sheet.
This simplifies the structure of the seat heater 20.
[0103] FIG. 13 is a plan view illustrating a seat heater 20A
according to a modified embodiment. As shown in FIG. 13, the seat
heater 20A has the heater electrodes 21, 22, the heating elements
23, 24, and the sensor electrode 25 formed between the insulation
sheets 26 and 28 bonded with each other.
[0104] The sensor electrode 25 has sensor portions 25a shaped into
a rectangle with a lengthwise direction being directed in the
X-axis direction and patterned in such a manner as to be disposed
at both ends of the heater electrodes 21, 22 and the heating
elements 23, 24.
[0105] When the insulation sheets 26, 28 covering the heater
electrodes 21, 22, the heating elements 23, 24 and the sensor
electrode 25 from the top-face side (+Z side) and the bottom-face
side (-Z side) are folded along a dotted lines L1 and L2 indicated
in FIG. 13, the seat heater 20 can be shaped as shown in FIG. 14.
According to the seat heater 20 shown in FIG. 14, the heater
electrodes 21, 22 and the heating elements 23, 24 are disposed at
the top-face side, while the sensor portions 25a of the sensor
electrode 25 are disposed at the bottom-face side.
[0106] The seat heater 20A including the heater electrodes 21, 22,
the heating elements 23, 24, and the sensor electrode 25 of the
modified example can be also used as the seat heaters of the
above-explained first and second embodiments. According to this
seat heater 20A, the heater electrodes 21, 22, the heating elements
23, 24, and the sensor electrode 25 can be formed in an integral
manner, the production costs can be reduced.
[0107] Moreover, as shown in FIG. 14, a spacer 29 may be disposed
between the heater electrodes 21, 22, the heating elements 23, 24
and the sensor electrode 25. According to such a structure, by
adjusting the thickness of the spacer 29, the tuning or the like of
the capacitance between the heater electrodes 21 and 22 and the
sensor electrode 25 is facilitated.
[0108] Furthermore, the seat heater 20A may be used in such a way
that the sensor electrode 25 is located at the top-face side, while
the heater electrodes 21 and 22 are located at the bottom-face
side.
[0109] According to the above-explained embodiments, information on
the determination result by the detection unit 33 is output to the
external device. The present invention is not limited to this
configuration, and the information on the determination result by
the detection unit 33 may be output to the heater unit 32. This
allows the heater unit 32 to stop energizing the heater electrodes
21 and 22 when, for example, no occupant 120 is seated on the seat
101. This suppresses unnecessary power consumption.
[0110] Moreover, the heater unit 32 may obtain information on the
in-phase component I from the detection unit 33, and may determine
that the seat 101 is moistened when the in-phase component I
exceeds a threshold to continue energizing the heater electrodes 21
and 22. According to such a configuration, the drying of the seat
101 can be prompted, thereby improving the detection precision of
the occupant 120 seated on the seat 101.
[0111] A temperature measuring resistor PT for detecting the
temperature of the seat 101 may be formed on the top face of the
insulation sheet 26 or the insulation sheet 27. This allows the
detection unit 33 to detect the temperature of the seat 101 from
the resistance of the temperature measuring resistor PT, and to
correct the threshold for determining whether or not the occupant
120 is seated on the seat 101 in consideration of the detected
temperature.
[0112] The temperature of the seat 101 may be detected based on the
resistance of the heating elements 23, 24 obtained through the
heater electrodes 21, 22, and the threshold for determining whether
or not the occupant 120 is seated on the seat 101 may be corrected
in consideration of the detected temperature.
[0113] The detection unit according to the above-explained
embodiments may be configured by hardware resources, or may be a
computer or a microcomputer configured by a CPU (Central Processing
Unit), a main memory, and an auxiliary memory.
[0114] According to the above-explained embodiments, the
explanation was given of the case in which the seat heater 20 is
installed in the seat 101 of the vehicle 100. The present invention
is not limited to this case, and the seat heater 20 may be
installed in the vehicle 100 other than the seat 101.
[0115] Various embodiments and modifications are available to the
present invention without departing from the broad sense of spirit
and scope of the present invention. The above-described embodiments
are given for explaining the present invention and do not confine
the scope of the present invention. In other words, the scope of
the present invention is set forth by the scope of claims, not by
the embodiments. Various modifications made within the scope of
claims and scope of significance of the invention equivalent
thereto are considered to fall under the scope of the present
invention.
[0116] This application is based on Japanese Patent Application No.
2010-176823 filed on Aug. 5, 2010. The entire specification, claims
and drawings of Japanese
[0117] Patent Application No. 2010-176823 are herein incorporated
in this specification by reference.
INDUSTRIAL APPLICABILITY
[0118] The heating system of the present invention is suitable for
warming the occupant and for detecting the occupant.
DESCRIPTION OF REFERENCE NUMERALS
[0119] 10, 10A Heating system [0120] 20, 20A Seat heater [0121] 21,
22 Heater electrode [0122] 21a, 22a Connection part [0123] 23, 24
Heating element [0124] 25 Sensor electrode [0125] 25a Sensor
portion [0126] 26 to 28 Insulation sheet [0127] 29 Spacer [0128] 32
Heater unit [0129] 33, 33A Detection unit [0130] 33a AC power
source [0131] 33b Quadrature demodulator [0132] 33c Detector [0133]
34A AC power source [0134] 34B AC power source [0135] 100 Vehicle
[0136] 101 Seat [0137] 101a Seating surface [0138] 120 Occupant
[0139] AR1, AR2 Area [0140] C1 to C8, Ca to Cf Capacitor [0141] L
Curve [0142] P1 to P4 Point [0143] PT Temperature measuring
resistor [0144] Ra to Rc Resistor [0145] SW1, SW2 Switch
* * * * *